Ubuntu - IPv6 - Special IPv6 address ranges

IPv6 addressPrefix length (bits)DescriptionNotes
::128unspecifiedUsed for default route and router solicitations. cf. 0.0.0.0 in IPv4
::1128loopback addresscf. 127.0.0.1 in IPv4
::ffff:a.b.c.d96IPv4 mapped IPv6 addressThe lower 32 bits are the IPv4 address. Used in socket API's to represent IPv4 hosts.
fe80::10link-localUnroutable autoconfigured addresses used on a LAN, e.g. for DHCPv6
fc00::7unique localAddresses used only within an autonomous system, unroutable globally. Cf. RFC 1918 addresses such as used in NAT.
ff00::8multicast
2000::3global unicastAll global unicast addresses currently begin with 2.

Some IPv6 address prefixes have been deprecated, and should no longer be used.

Deprecated IPv6 addressPrefix length (bits)DescriptionNotes
3ffe::166bone prefixUsed 1998-2006.
::a.b.c.d96embedded IPv496 zero bits followed by 32 IPv4 bits. Also called “IPv4 compatible IPv6 address”. Replaced by mapped addresses.
fec0::10site-localReplaced by Unique Local Addresses

Some address prefixes are special use:

Special IPv6 addressPrefix length (bits)DescriptionNotes
2001:db8::32documentation examplesNot to be routed.
2001:0::32Teredo tunnelsThe remaining bits come from a Teredo server and the client NAT device.
2002::166to4 tunnelsThe next 32 bits are the client IPv4 address